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Idris H.,Engility Corporation
15th AIAA Aviation Technology, Integration, and Operations Conference | Year: 2015

Choke points in the national airspace system are resources for which demand exceeds capacity and hence generate delays that propagate through the system network. Under nominal conditions, airports, and more specifically runways, are the main choke points that generate most delays. A historical data analysis is conducted in order to compare and rank the major airports of the national airspace system. A number of metrics and techniques are used in order to isolate locally generated delays, which demonstrate choke point effects, from delays that are propagated from other airports. Namely, throughput saturation is used to quantify how severely demand exceeds capacity, delay relative to unimpeded travel time is used to quantify queuing effects, and passing is used to isolate the local queuing delays from delays due to control activity to conform to downstream constraints. Results provide insights on how the major airports compare in terms of generating delay locally versus manifesting propagated delay. © 2015, American Institute of Aeronautics and Astronautics Inc. Source


Ahlstrom U.,Technical Center | Jaggard E.,Engility Corporation
Transportation Research Part C: Emerging Technologies | Year: 2010

Adverse weather conditions are hazardous to flight and contribute to re-routes and delays. This has a negative impact on the National Airspace System (NAS) due to reduced capacity and increased cost. In today's air traffic control (ATC) system there is no automated weather information for air traffic management decision-support systems. There are also no automatic weather decision-support tools at the air traffic controller workstation. As a result, air traffic operators must integrate weather information and traffic information manually while making decisions. The vision in the Next Generation Air Transportation System (NextGen) includes new automation concepts with an integration of weather information and decision-making tools. Weather-sensitive traffic flow algorithms could automatically handle re-routes around weather affected areas; this would optimize the capacity during adverse conditions. In this paper, we outline a weather probe concept called automatic identification of risky weather objects in line of flight (AIRWOLF). The AIRWOLF operates in two steps: (a) derivation of polygons and weather objects from grid-based weather data and (b) subsequent identification of risky weather objects that conflict with an aircraft's line of flight. We discuss how the AIRWOLF concept could increase capacity and safety while reducing pilot and air traffic operator workload. This could translate to reduced weather-related delays and reduced operating costs in the future NAS. Source


Sinclair A.J.,Auburn University | Sherrill R.E.,Engility Corporation | Lovell T.A.,Air Force Research Lab
Journal of Guidance, Control, and Dynamics | Year: 2015

The improvements in performance, reduction of fuel consumption, and extension of the domain of validity of linearized control laws using calibrated Cartesian coordinates are studied. First, the Cartesian coordinate calibration is reviewed. Next, a linear-quadratic control law designed using linearized dynamics is reviewed, and the implementation of this control law in the presence of nonlinear dynamics. Finally, single-impulse rendezvous design using linearized dynamics is reviewed, and the implementation of the maneuver in the presence of nonlinear dynamics is illustrated. However, the calibrated states seem to be more effective for continuous low-thrust control than for impulsive maneuver design. As mentioned, it may be more accurate to solve for the impulsive maneuver using an iterative process. Source


Richardson A.S.,U.S. Navy | Swanekamp S.B.,U.S. Navy | Schumer J.W.,U.S. Navy | Ottinger P.F.,Engility Corporation
IEEE Transactions on Plasma Science | Year: 2013

In a pinched-beam ion diode, an intense electron beam focuses on-axis at the center of the anode and passes through the thin anode foil into a beam dump region behind the anode foil. The beam dump usually consists of an evacuated cylindrical anode-can. Because of energy deposition from the intense electron beam, the interior surfaces of the anode-can are expected to be space-charge-limited emitters. Therefore, the electron space charge from the beam in the anode-can will draw ions off these surfaces. There is evidence from nuclear activation which suggests that ions exist in the anode-can with energies that significantly exceed those associated with the diode voltage. Analysis and particle-in-cell simulations show that a virtual cathode can form in the anode-can that accelerates ions up to the energy associated with the diode voltage. Additionally, a subset of these ions can form current bursts that are driven to the outer wall of the anode-can with ion energies as high as a few times the energy associated with the diode voltage. © 1973-2012 IEEE. Source


Carter J.,Indiana University - Purdue University Indianapolis | Grommon E.,Indiana University - Purdue University Indianapolis | Harris P.,Engility Corporation
Physical Communication | Year: 2016

Programming, management, and interoperability of land mobile radios within the public safety sector have long been salient issues for policymakers, practitioners, service vendors, and scholars. Despite receiving substantial attention in the form of government expenditure and agency task forces, there has only been moderate advancement in this concerning area. Recently, as part of a US Department of Justice-funded effort, an innovative technology known as wireless broadband over-the-air-programming (OTAP) has been translated from a conceptual model to an operational deployment. OTAP technology holds significant promise to enhance the management of public safety communications via land mobile radios. This research presents the concept of OTAP, the engineering behind the recently developed broadband enabled OTAP prototype, and conceptualizes how this technology can impact the processes used to facilitate public safety interoperability within the context of portable radio programming. © 2016 Elsevier B.V. Source

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